A belt conveyor for conveying various materials such as powdery materials, granular materials, or lumpy materials includes two sets of pulleys provided at a start end portion and a terminal end portion, respectively, an endless loop belt wrapped around the pulleys, and a drive means for rotating the drive pulley. The drive means causes the drive pulley to revolve the belt. Thereby, the materials put on a carrier belt are conveyed from the start end to the terminal end. At the terminal end pulley, the belt makes a U-turn in a downward direction, the return belt moves from the terminal end to the start end, and the belt makes a U-turn in an upward direction at the start end pulley.
The surface of the belt conveyor on which the materials are put is a dirty surface. In a case where the return belt is placed such that the dirty surface faces downward, the materials scatter from the dirty surface of the return belt and contaminate a floor surface or the like. To avoid this, conventionally, belt reversing mechanisms are provided at the upstream portion and the downstream portion of the return belt, respectively, in a direction in which the belt moves. The belt reversing mechanism at the upstream portion reverses the belt 180 degrees to cause the dirty surface to face upward, while the belt reversing mechanism at the downstream portion reverses the belt back to the state where the dirty surface faces downward. In this state, the belt moves toward the start end pulley.
In a belt reversing apparatus of a belt conveyor disclosed in Japanese Utility Model Application Publication No. Hei. 2-10306, two sets of belt reversing mechanisms each including a guide roller mechanism having sixth rollers arranged annularly are provided to be spaced apart from each other and are adapted to guide the belt such that the belt is retained to have a tubular open cross-section. In addition to retaining the belt to have the tubular open cross-section, an example in which the belt is retained to have a flat U-shaped cross-section is disclosed.
A belt reversing apparatus of a belt conveyor disclosed in Japanese Patent No. 2808351 includes two sets of pinch rollers which are provided at both end portions to support the belt from upper and lower surfaces, and plural reversing guide units (guide roller mechanisms) including plural rollers arranged annularly between these pinch rollers to respectively guide the belt such that the belt is retained to have a tubular open cross-section.